The present invention relates to a linear motion guide device, and more particularly, to a linear roller guide device using rollers as rolling elements.
The conventional linear roller guide device of this type generally has a structure in which a movable block is movably supported on a track rail through a number of rollers. The guide device using rollers has an advantage of high rigidity and high load bearing ability in comparison with the guide device using balls. The movable block comprises a block body and side covers to be attached to both end portions of the block body. The block body is provided with a roller rolling surface and a roller returning passage for endlessly circulating a roller row, and the side cover is provided with a direction changing passage for connecting the roller rolling surface side to the roller returning passage.
Both sides of the roller rolling surface of the movable member are provided with a roller end surface guide wall for guiding an end surface of the roller, and each of the roller returning passage and the direction changing passage is also provided with a guide wall which is formed to be continuous to the roller end surface guide wall, whereby the end surfaces of the roller are guided in entire circulating passage so as to orderly circulate the rollers.
Conventionally, as to structural members such as the roller returning passage, the side cover and the roller end surface guide wall or the like, an attempt to reduce a manufacturing cost has been made by employing resin moldings as the structural members.
However, the above conventional linear roller guide devices entail drawbacks as described hereunder:
{circle around (1)} The manufacturing process is complicated.
That is, each of the resin molded members is a molded member which is formed separately from the block body, so that a process of assembling the respective resin molded members is required after separately forming the respective members.
{circle around (2)} The circulating defects of the roller at the roller rolling surface are liable to occur.
Namely, when assembled the resin molded members, irregularities are liable to occur at a connecting portion between the roller returning passage and the direction changing passage, and at a connecting portion between the roller rolling surface and the direction changing passage, so that there may be posed a problem, for example, that a smooth circulation of the rollers is obstructed and a problem of generation of an abnormal noise.
{circle around (3)} The circulating defects of the roller at the roller end surface are liable to occur.
In particular, in case of the roller, it is required to prevent skew of the roller (i.e. blurring of a rotational axis of the roller). In order to prevent the skew, it is required to guide the end surface of the roller not only in a range of a loaded area of the roller rolling surface but also in all around of an endlessly circulating passage ranging from the direction changing passage to the non-loaded area of the roller returning passage.
FIG. 15(a) shows a state that the roller 100 changes a rolling direction thereof form an unloaded area xcex1 to a loaded area xcex2 of the direction changing passage. At the time of direction changing of the roller 100, for example, as schematically shown in FIGS. 15(b) and 15(c), when the roller 100 moves from the loaded area xcex1, and then enters into the loaded area xcex2 in a skewed state, one end portion of the roller 100a of the roller 100 will firstly collide against the roller rolling surface 101 in the loaded area, so that the smooth movement of the roller 100 is obstructed. In addition, an edge load may occur at the end portion 100a of the roller 100 entering into the loaded area xcex2, so that the roller 100 per se and the roller rolling surface 101 are damaged thereby to deteriorate durability of the guide device. Further, vibration of the roller and changes in rolling resistance during the circulation of the rollers will occur thereby to obstruct the smooth circulation of the rollers.
In order to prevent such problems, hitherto, the end surface of the roller is formed so as to be guided by the roller end surface guide wall provided at both sides of the roller rolling surface and passage walls provided at the direction changing passage and the roller returning passage. However, since the guide system is formed by connecting the discontinuous roller end surface guide wall, direction changing passage and roller returning passage, a sticking of the roller is liable to occur due to non-uniformity in a width of the respective passages and the irregularities of the connected portions thereby to also obstruct the smooth circulation of the rollers.
{circle around (4)} A falling-out of the roller is required to be prevented.
On the other hand, hitherto, in order to prevent the roller from failing out from the movable block when the movable block is detached from the track rail, there is a well known structure in which a chamfered portion is provided at end portion of the roller and an engaging projection with which the chamfered portion is engaged is provided at the roller end surface guide wall formed along the roller rolling surface.
However, in case of such roller retaining system, when the engaging projection interferes with the roller during the circulation of the roller, the smooth circulation of the roller is obstructed. Therefore, when assembling the guide device, it is required to provide a small gap or clearance between the roller and the engaging projection so as not to interfere the engaging projection with the roller. However, it was difficult to provide the engaging projection to an accurate position.
In addition, the chamfered portion is required to be provided, so that an effective length for bearing the load is disadvantageously shortened in a length corresponding to the length of the chamfered portion, thereby to lower the load bearing ability.
On the other hand, there is also another well-known roller retaining system in which a number of rollers are retained in form of a chain by linking the rollers in a roller chain. However, in the case of such rollers retained in the roller chain, a problem of a running-out of the roller chain will arise during the circulation of the rollers. Therefore, it is necessary to guide the roller chain along the predetermined track. However, it was difficult to accurately guide the roller chain.
The first invention has been achieved for solving the problems described above, and an object of this invention is to provide a linear roller guide device enabling to reduce the assembling processes, to accurately position the structural members to a predetermined positions of the block body, and to secure the smooth circulation of the rollers by integrally forming at least one of the roller returning passage, roller end surface guide wall and direction changing passage with the block body.
An object of the second invention is, in addition to the object described above, to provide a linear roller guide device enabling to securely prevent the roller chain from running-out during the circulation of the rollers linked by the roller chain.
In order to achieve the afore-mentioned object, the first invention provides a linear roller guide device comprising a track rail and a movable block assembled to the track rail through a number of rollers,
the movable block comprising:
a roller rolling surface on which the rollers roll;
a block body having a roller returning passage corresponding to the roller rolling surface;
a direction changing passage inner periphery portion formed to both end surfaces of the block body;
a pair of roller end surface guide walls formed to both sides of the roller rolling surface of the block body and adapted to guide both the end surfaces of the roller; and
side covers each having a direction changing passage outer periphery portion for forming a direction changing passage by fitting the side cover into the direction changing passage inner periphery portion formed to both end surfaces of the block body,
the track rail including a roller rolling surface extending in an axial direction corresponding to the roller rolling surface of the block body, and
the rollers circulating in an endless circulating passage constituted by a loaded area between the roller rolling surface of the block body and the roller rolling surface corresponding to the track rail, the direction changing passage and the roller returning passage,
wherein at least one of a roller returning passage forming member for forming the roller returning passage, a roller end surface guide wall forming member for forming at least one of the paired roller end surface guide wall and a direction changing passage inner periphery portion forming member for forming the direction changing passage inner periphery portion is formed as a molded body integrally formed with the block body by inserting the block body into a molding die.
According to the structure described above, the assembling of the roller end surface guide wall forming member, the roller returning passage forming member and the direction changing passage inner periphery portion forming member is not required, thus eliminating the assembling process for the members.
In addition, the roller end surface guide wall, the roller returning passage and the direction changing passage inner periphery portion can be formed at accurate positions with respect to the block body.
After the rollers are rolled from a starting end to a terminal end of the roller rolling surface of the block body, the rollers are rolled and moved to the roller returning passage through the direction changing passage, moved along the roller returning passage, and thereafter, supplied to the starting end side of the roller rolling surface through the direction changing passage formed at the other side of the roller rolling surface.
When the direction changing passage inner periphery portion forming member is integrally formed with the block body, it becomes possible to eliminate the irregularities to be formed at the connected portion between the roller rolling surface and the direction changing passage inner periphery portion. In addition, as to the roller returning passage forming member, when it is integrally formed with the block body, it also becomes possible to eliminate the irregularities to be formed at the connected portion between the direction changing passage inner periphery portion and the roller returning passage.
Further, in one aspect of this invention, the device may have a structure in which the roller returning passage and the direction changing passage inner peripheral portion are provided with guide walls for guiding the end surface of the roller, the guide wall being continuous to the roller end surface guide wall, and the roller returning passage, the roller end surface guide wall of at least one of the paired roller end surface guide walls and the direction changing passage inner peripheral portion are integrally formed with the block body.
According to the structure described above, the roller end surface guide walls of the roller returning passage and the direction changing passage in an unloaded area and the roller end surface guide wall to be formed along the roller rolling surface in loaded area can be continuously molded, so that the irregularities are not formed at the connected portions in all around the endless circulating passage, thus enables the end surface of the roller to smoothly move.
In addition, the gap or clearance between the guide wall and the roller end surface can be formed with high accuracy in all around the endless circulating passage, so that the generation of the skew of the roller can be securely prevented.
In another aspect of this invention, the device may have a structure in which a chamfered portion is provided at least one end portion of the roller and an engaging projection with which the chamfered portion of the roller is engaged is provided at the roller end surface guide wall integrally molded with the block body so as to prevent the roller from falling out.
As described above, when such engaging projection is provided at the roller end surface guide wall to be integrally molded with the block body, the engaging projection can be accurately positioned with respect to the block body, so that the falling-out of the roller can be securely prevented even if the bearing block is detached from the track rail. In addition, there is not the slightest fear of interference of the block body with the roller during the circulation of the roller.
The guide device has a structure having four rows of rollers in total in which a pair of right and left rows of rollers are disposed to be rollable between the upper surface of the track rail and a lower surface of a horizontal portion of the block body and other two rows of the rollers each is disposed between the right and left side surfaces of the track rail and an inside surfaces of a suspending portion of the block body, respectively.
In this case, it is preferable that a contact angle line constituted by a line connecting two contact points of the roller disposed between the corresponding roller rolling surfaces formed to the upper surface of the track rail and the horizontal portion of the block body is set to vertically extend with an inclination angle of about 90xc2x0 with respect to a horizontal line, while a contact angle line of the roller disposed between the corresponding roller rolling surfaces formed to the right and left side surfaces of the track rail and the inside surfaces of the suspending portion of the block body is set to obliquely extend downwards and is formed so as to incline with an inclination angle of 30xc2x0 with respect to a horizontal line.
In still another aspect of this invention, the guide device has a structure having four rows of rollers in total in which two rows of rollers are vertically disposed to be rollable between a right side surface of the track rail and a right inside surface of the suspending portion of the block body, and vertically disposed to be rollable between a left side surface of the track rail and a left inside surface of the suspending portion of the block body, respectively.
Among the two rows of the rollers arranged vertically at upper and lower portions, it is preferable that the upper row of rollers is formed so that a contact angle line of the roller is set to obliquely extend upwards from a side of the track rail to sides of the right and left suspending portions of the block body, and is formed so as to incline with an inclination angle of almost 45xc2x0 with respect to a horizontal line, while the lower row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards, and is formed so as to incline with an inclination angle of almost 45xc2x0, or that the upper row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards from a side of the track rail to sides of the right and left suspending portions of the block body, and is formed so as to incline with an inclination angle of almost 45xc2x0 with respect to a horizontal line, while the lower row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards, and is formed so as to incline with an inclination angle of almost 45xc2x0.
In particular, at a time of an insert molding, when a block supporting portion corresponding to the roller rolling surface of the block body is provided to an inner periphery of a molding die and the roller rolling surface is contacted to the block supporting portion, the block body can be effectively positioned in the molding die.
According to such structure, a pair of right and left roller rolling grooves (surfaces) of the block body will contact to the block supporting portion. As a result, the block body is supported by the paired right and left block supporting portions so that the block body is clamped from every four directions and supported by four points. Therefore, even if an injection pressure of a molding material is applied to the block body from every directions, the block body can be held unmoved, and the burr is not formed at a portion between the roller rolling surface and the block supporting portion.
In a second invention, there is provided a linear roller guide device comprising a track rail and a movable block assembled to the track rail through a number of rollers,
the movable block comprising:
a block body having a roller rolling surface and a roller returning passage corresponding to the roller rolling surface;
a direction changing passage inner periphery portion formed to both end surfaces of the block body; and
side covers each having a direction changing passage outer periphery portion for forming a direction changing passage by fitting the side cover into the direction changing passage inner periphery portion formed at both end surfaces of the block body,
the track rail including a roller rolling surface extending in an axial direction corresponding to the roller rolling surface of the block body,
the rollers circulating in an endless circulating passage constituted by a loaded area between the roller rolling surface of the block body and the roller rolling surface corresponding to the track rail, the direction changing passage and the roller returning passage, and the rollers are linked to each other by a roller chain inserted to be movable in the endless circulating passage,
wherein the roller returning passage and the direction changing passage inner periphery guide portion are provided with a roller chain guide portion for guiding a track of the roller chain onto a predetermined track,
wherein at least one of the roller returning passage forming member for forming the roller returning passage and the direction changing passage inner periphery portion forming member for forming the direction changing passage inner periphery portion is integrally molded by inserting the block body into a molding die.
According to the structure described above, the rollers can be smoothly rolled and moved in the endless circulating passage while being kept in a state where center axes of the respective rollers are retained in parallel to each other and intervals of adjacent rollers are retained in a predetermined distance, thus enabling to prevent the skew-generation.
In addition, the roller chain is guided onto the predetermined track by the roller chain guide portions formed to the roller returning passage and the direction changing passage, and the rollers shall be accurately guided by the roller chain guided by the roller chain guide portion. Further, a run-out of the roller chain can be prevented by the roller chain guide portion.
In addition, when the roller returning passage forming member for forming the roller returning passage and the direction changing passage inner periphery portion forming member for forming the direction changing passage inner periphery portion to which the roller chain guide portions are formed are integrally molded with the block body, the roller chain guide portions can be formed on accurate positions of the track.
In addition, when the direction changing passage inner periphery portion forming member is integrally formed with the block body, it becomes possible to eliminate the irregularities to be formed at the connected portion between the roller rolling surface and the direction changing passage inner periphery portion. Further, as to the roller returning passage, when it is integrally formed with the block body, it also becomes possible to eliminate the irregularities to be formed at the connected portion between the direction changing passage inner periphery portion and the roller returning passage. As a result, the rollers can be further smoothly circulated and moved in cooperation with the guiding function of the roller chain.
Furthermore, when the roller chain is formed so as to have an endless structure and is provided with a falling-out preventing portion for the rollers, the falling-out of the rollers can be prevented by the roller chain even if the movable block is detached from the track rail.
Further, the roller chain is preferably provided with a guide projecting portion so as to project from the end surface of the roller in an axial direction of the roller, while the roller returning passage and the direction changing passage inner peripheral portion are preferably provided with guide grooves with which the guide projecting portion is engaged. In addition, at least one side of the roller rolling surfaces formed to the block body is preferably provided with a guide wall having the guide groove extending in parallel to the roller rolling surface for guiding the guide projecting portion in parallel to the roller rolling surface. As to this guide wall, it is also preferable to integrally mold the guide wall with the block body by using an insert molding method and to continuously form the guide groove to the roller returning passage, the direction changing passage inner periphery portion and the guide wall so that the guide groove ranges to all around the endless circulating passage.
According to the structure described above, when the roller chain is circulated and moved, the guide projecting portion is engaged with the guide groove formed to the roller returning passage and the direction changing passage inner peripheral portion, so that the run-out of the roller chain is suppressed. As a result, the rollers can be rolled and moved in orderly arranged state in all around the endless circulating passage.
In addition, in a case where the roller chain is formed in a striped-shape having no connected portion at both ends thereof, when the movable block is detached from the track rail, the guide projecting portion is engaged with the guide groove, thus enabling to prevent a sagging or slack of an end portion of the roller chain. Further, also in a case of the roller chain having an endless structure, the sagging or slack of an intermediate portion of the roller chain can be prevented.
In still another aspect of this invention, the roller chain comprises spacer portions disposed between the adjacent rollers and connecting portions for connecting the respective spacer portions, and the guide projecting portion is provided to the connecting portion.
Accordingly, each of the rollers is arranged and circulated in a state where the rollers are retained by the spacer portions form back and forth in the arranging direction thereof.
Further, when a falling-out preventing portion for the roller is provided to the spacer portion so as to prevent the falling-out of the roller from back and forth of the roller, it becomes unnecessary to chamfer the end portion of the roller, so that an effective length of the roller for bearing the load can be increased.
Furthermore, since only the spacer portion is disposed between the adjacent rollers, a pitch of the rollers can be formed as small as possible, so that a number of the rollers to be disposed per unit length for bearing the load can be increased as many as possible, thus improving the load bearing ability of the roller.
In still another aspect of this invention, the connecting member and the spacer portion disposed between the adjacent rollers are formed as resin moldings, the roller is formed to have a hollow portion, and the roller is retained by inserting a resin portion into the hollow portion of the roller.
According to the structure described above, the falling-out of the roller can be surely prevented and a degree of parallelization between the adjacent rollers can be accurately maintained.
In addition, the roller may be retained in such a manner that a recessed portion is formed to both end portions of the roller and the resin portion is inserted into the recessed portion or in a manner that a grooved portion is formed to a center peripheral portion of the roller and the resin portion is fitted into the grooved portion.
When the roller chain moves at portion between the roller rolling surfaces and the unloaded roller rolling passage, the roller chain takes a linear shape. In contrast, when the roller chain moves in the direction changing passage, the roller chain is deformed from linear-shape to a curved-shape. As a result, the roller chain is repeatedly deformed in accordance with the movement of the movable block.
In view of this point, it is preferable to reinforce the roller chain by inserting a wire or thin plate into the connecting member.
In the guide device of the present invention, the number of rollers and arrangement thereof are optional. However, the following arrangements are more effective.
That is, the guide device may have a structure having four rows of rollers in total in which a pair of right and left rows of rollers are disposed to be rollable between the upper surface of the track rail and a lower surface of a horizontal portion of the block body, and one row of the roller is disposed between the right and left side surfaces of the track rail and inside surfaces of a suspending portion of the block body, respectively.
In this case, it is preferable that a contact angle line constituted by a line connecting two contact points of the roller disposed between the corresponding to the roller rolling surfaces formed to the upper surface of the track rail and the horizontal portion of the block body is set to vertically extend with an inclination angle of about 90xc2x0 with respect to a horizontal line, while a contact angle line of the roller disposed between the corresponding roller rolling surfaces formed to the right and left side surfaces of the track rail and the inside surfaces of the suspending portion of the block body is set to obliquely extend downwards and is formed so as to incline with an inclination angle of 30xc2x0 with respect to a horizontal line.
In addition, the guide device may have a structure having four rows of rollers in total in which two rows of rollers are vertically disposed at upper and lower portions to be rollable between a right side surface of the track rail and a right inside surface of the suspending portion of the block body, and vertically disposed to be rollable between a left side surface of the track rail and a left inside surface of the suspending portion of the block body, respectively.
Among the two rows of the rollers arranged vertically, it is preferable that the upper row of rollers is formed so that a contact angle line of the roller is set to obliquely extend upwards from a side of the track rail to sides of the right and left suspending portions of the block body and is formed so as to incline with an inclination angle of almost 45xc2x0 with respect to a horizontal line, while the lower row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards, and is formed so as to incline with an inclination angle of almost 45xc2x0; or that the upper row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards from a side of the track rail to sides of the right and left suspending portions of the block body and is formed so as to incline with an inclination angle of almost 45xc2x0 with respect to a horizontal line, while the lower row of rollers is formed so that a contact angle line of the roller is set to obliquely extend downwards and is formed so as to incline with an inclination angle of almost 45xc2x0.
In particular, at a time of an insert molding, when a block supporting portion corresponding to the roller rolling surface of the block body is provided to an inner periphery of a molding die and the roller rolling surface is contacted to the block supporting portion, the block body can be effectively positioned in the molding die.
According to such structure, a pair of right and left roller rolling grooves (surfaces) of the block body will contact to the block supporting portion. As a result, the block body is supported by the paired right and left block supporting portions so that the block body is clamped from every four directions and supported by four points. Therefore, even if an injection pressure of a molding material is applied to the block body from every directions, the block body can be held unmoved, and the burr is not formed at a portion between the roller rolling surface and the block supporting portion.